Dual top gas feed through distributor for high density plasma chamber

ABSTRACT

A gas distributor for use in a semiconductor process chamber comprises a body. The body includes a first channel formed within the body and adapted to pass a first fluid from a first fluid supply line through the first channel to a first opening. A second channel is formed within the body and adapted to pass a second fluid from a second fluid supply line through the second channel to a second opening. The first and second openings are arranged to mix the fluids outside the body after the fluids pass through the openings.

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of semiconductorprocessing equipment. More particularly, the present invention relatesto methods and apparatus for depositing thin films, for example with gasdistributors, used in the formation of integrated circuits.

One of the primary steps in the fabrication of modem semiconductordevices is the formation of a film, such as a silicon oxide film, on asemiconductor substrate. Silicon oxide is widely used as dielectriclayer in the manufacture of semiconductor devices. As is well known, asilicon oxide film can be deposited by a thermal chemical-vapordeposition (“CVD”) process or by a plasma-enhanced chemical-vapordeposition (“PECVD”) process. In a conventional thermal CVD process,reactive gases are supplied to a surface of the substrate, whereheat-induced chemical reactions take place to produce a desired film. Ina conventional plasma-deposition process, a controlled plasma is formedto decompose and/or energize reactive species to produce the desiredfilm.

Semiconductor device geometries have decreased significantly in sizesince such devices were first introduced several decades ago, andcontinue to be reduced in size. This continuing reduction in the scaleof device geometry has resulted in a dramatic increase in the density ofcircuit elements and interconnections formed in integrated circuitsfabricated on a semiconductor substrate. One persistent challenge facedby semiconductor manufacturers in the design and fabrication of suchdensely packed integrated circuits is the desire to prevent spuriousinteractions between circuit elements, a goal that has required ongoinginnovation as geometry scales continue to decrease.

Unwanted interactions are typically prevented by providing spacesbetween adjacent elements that are filled with a dielectric material toisolate the elements both physically and electrically. Such spaces aresometimes referred to herein as “gaps” or “trenches,” and the processesfor filling such spaces are commonly referred to in the art as “gapfill”processes. The ability of a given process to produce a film thatcompletely fills such gaps is thus often referred to as the “gapfillability” of the process, with the film described as a “gapfill layer” or“gapfill film.” As circuit densities increase with smaller featuresizes, the widths of these gaps decrease, resulting in an increase intheir aspect ratio, which is defined by the ratio of the gap's height toits depth. High-aspect-ratio gaps are difficult to fill completely usingconventional CVD techniques, which tend to have relatively poor gapfillabilities. One family of dielectric films that is commonly used to fillgaps in intermetal dielectric (“IMD”) applications, premetal dielectric(“PMD”) applications, and shallow-trench-isolation (“STI”) applications,among others, is silicon oxide (sometimes also referred to as “silicaglass” or “silicate glass”).

Some integrated circuit manufacturers have turned to the use ofhigh-density plasma CVD (“HDP-CVD”) systems in depositing silicon oxidegapfill layers. Such systems form a plasma that has a density greaterthan about 10¹¹ ions/cm³, which is about two orders of magnitude greaterthan the plasma density provided by a standard capacitively coupledplasma CVD system. Inductively coupled plasma (“ICP”) systems areexamples of HDP-CVD systems. One factor that allows films deposited bysuch HDP-CVD techniques to have improved gapfill characteristics is theoccurrence of sputtering simultaneous with deposition of material.Sputtering is a mechanical process by which material is ejected byimpact, and is promoted by the high ionic density of the plasma inHDP-CVD processes. The sputtering component of HDP deposition thus slowsdeposition on certain features, such as the corners of raised surfaces,thereby contributing to the increased gapfill ability.

Even with the use of HDP and ICP processes, there remain a number ofpersistent challenges in achieving desired deposition properties. Theseinclude the need to manage thermal characteristics of the plasma withina processing chamber, particularly with high-energy processes that mayresult in temperatures that damage structures in the chamber. Inaddition, there is a general desire to provide deposition processes thatare uniform across a wafer. Nonuniformities lead to inconsistencies indevice performance and may result from a number of different factors.The deposition characteristics at different points over a wafer resultfrom a complex interplay of a number of different effects. For example,the way in which gas is introduced into the chamber, the level of powerused to ionize precursor species, the use of electrical fields to directions, and the like, may ultimately affect the uniformity of depositioncharacteristics across a wafer. In addition, the way in which theseeffects are manifested may depend on the physical shape and size, of thechamber, such as by providing different diffusive effects that affectthe distribution of ions in the chamber.

One particular challenge with HDP and ICP processes is the management ofchemical reactions during the deposition process so that the chemicalcharacteristics of the layer deposited with the HDP/CVD process areuniform across the area wafer. In particular, work in connection withthe present invention suggests that incomplete reaction of SiH₄ with O₂can lead to the deposition of disproportionate amounts of Si over someregions of a coated wafer, for example excessive Si deposited centrallyso that the coating is “silicon rich” centrally. As the chemicalcharacteristics of a deposited layer are related to the physicalproperties of the layer, for example dielectric properties andresistance to etching, it would be desirable to provide deposited layerswith uniform chemical. Although prior techniques to provide uniformchemical reactions and depositions by injecting both SiH₄ and O₂ intothe processing chamber have met with some success, further improvementsin the chemical uniformity of deposited layers is continually sought.

There is accordingly a general need in the art for improved systems forgenerating plasma that improve deposition across wafers in HDP and ICPprocesses.

BRIEF SUMMARY OF THE INVENTION

According to the present invention, methods and apparatus related to thefield of semiconductor processing equipment are provided. Moreparticularly, the present invention relates to methods and apparatus fordepositing thin films, for example with gas distributors. Merely by wayof example, the methods and apparatus of the present invention are usedin HDP/CVD processes. The methods and apparatus can be applied to otherprocesses for semiconductor substrates, for example those used in theformation of integrated circuits.

In one embodiment of the present invention, a gas distributor for use ina semiconductor process chamber comprises a body. The body includes afirst channel formed within the body and adapted to pass a first fluidfrom a first fluid supply line through the first channel to a firstopening. A second channel is formed within the body and adapted to passa second fluid from a second fluid supply line through the secondchannel to a second opening. The first and second openings are arrangedto mix the fluids outside the body after the fluids pass through theopenings.

In another embodiment of the present invention, a gas distributor foruse in a semiconductor process chamber comprises a body. The bodyincludes a lower surface, and a plurality of first openings disposed onthe lower surface. The openings are adapted to pass a first fluid from afluid first supply line to the chamber. A second opening is disposed onthe lower surface and adapted to pass a second fluid from a second fluidsupply line. The first openings are disposed around the second openingand arranged to mix the fluids outside the body after the fluids passthrough the openings.

In yet another embodiment of the present invention, a method ofdepositing a thin film in a semiconductor process chamber comprisespassing a first fluid through a first channel. The first channel isdisposed within a body of a gas distributor. A second fluid is passedthrough a second channel disposed within the body of the gasdistributor. The first fluid remains separated from the second fluidwhile the fluids pass through the channels. The fluids are expelled fromthe channels to mix the first fluid with the second fluid outside thegas distributor and the first fluid undergoes a chemical reaction withthe second fluid outside the gas distributor.

In a further embodiment of the present invention, a device for use witha semiconductor process to deposit a layer on a semiconductor wafercomprises a top dome and a side wall positioned to define a chamber. Asupport is adapted to support the semiconductor wafer. A gas distributorcomprises a body that extends downward into the chamber centrally nearthe top dome. The body comprises a first channel formed therein and isadapted to pass a first fluid downward to a first opening into thechamber. The body comprising a second channel formed therein and isadapted to pass a second fluid downward through the gas distributor to asecond opening into the chamber. A first fluid supply line is coupled tothe first channel formed in the body of gas distributor. A second fluidsupply line is coupled to the second channel formed in the body of thegas distributor to separate the second fluid from the first fluid whilethe fluids are passed from the supply lines to the openings. Theopenings are adapted to mix the first fluid with the second fluidoutside the body of the gas distributor above the wafer support.

In a yet further embodiment of the present invention, a gas distributorfor use in a semiconductor process chamber comprises a body. The bodyincludes a channel adapted to pass a fluid from a fluid supply line toat least one opening. The body also includes a connector adapted toengage a support and hold the distributor and the at least one openingin a predetermined orientation relative to the support.

In another embodiment of the present invention, a gas distributor foruse in a semiconductor processor chamber comprises a body. The bodyincludes a first channel adapted to pass a first fluid from a firstfluid supply line to a first opening formed in the distributor. The bodyalso includes a second channel adapted to pass a second fluid from asecond fluid supply line to a second opening formed in the distributor.The body includes a connector that is adapted to engage a support andhold the distributor and the channels in a pre-determined orientationrelative to the support and the fluid supply lines.

In another embodiment of the present invention a method of installing agas distributor in a semiconductor process chamber comprises aligningthe gas distributor with a support in a first orientation of the gasdistributor. The gas distributor is rotated from the first orientationto a predetermined orientation to attach the gas distributor to thesupport. The gas distributor is rotated no more than half a turn fromthe first orientation to the pre-determined orientation.

Embodiments of the present invention provide improved uniformity in alayer of material deposited on a semiconductor substrate, for exampleimproved uniformity of an SiO₂ layer. In particular, embodiments of thepresent provide channels to inject a fluid, for example O₂ gas,centrally from a gas distributor to avoid deposition of a silicon richlayer centrally on the wafer.

A further understanding of the nature and advantages of the presentinvention may be realized by reference to the remaining portions of thespecification and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross-sectional view of a previously known gas distributor;

FIG. 1B is a simplified cross-sectional view of an exemplary ICP reactorsystem;

FIG. 2A shows cross sectional view of a gas distributor having twochannels formed therein to separately pass a first fluid and a secondfluid according to an embodiment of the present invention;

FIG. 2B shows a bottom view of the gas distributor as hi FIG. 2Aaccording to an embodiment of the present invention

FIG. 2C shows a cross sectional view of a connector for the gasdistributor as in FIGS. 2A and 2B connected to a support in asemiconductor process chamber according to an embodiment of the presentinvention;

FIG. 3A shows side cross sectional view of a quarter turn connector toattach a gas distributor in a predetermined orientation to a supportconnected to gas supply lines according to an embodiment of the presentinvention;

FIG. 3B shows an upward looking cross sectional view of the quarter turnconnector of FIG. 3A according to an embodiment of the presentinvention;

FIGS. 4A to 4C show installation of a quick turn connector on a gasdistributor into a gas supply line support according to an embodiment ofthe present invention;

FIG. 5 shows a method of processing a wafer with a gas distributorhaving two channels formed therein according to an embodiment of thepresent invention;

FIG. 6A shows a gas distributor with a first channel that comprisesseveral branches that extend to a plurality of first openings and asecond channel with several branches that extend to a plurality ofsecond openings according to an embodiment of the present invention;

FIG. 6B shows a bottom view of the gas distributor as in FIG. 6Aaccording to an embodiment of the present invention;

FIG. 6C illustrates a bottom view of the gas distributor as in FIGS. 6Aand 6B and the first channel and the several branches that extend to theplurality of first openings according to an embodiment of the presentinvention; and

FIG. 6D illustrates a bottom view of the gas distributor as in FIGS. 6Aand 6B and the second channel and the several branches that extend tothe plurality of second openings according to an embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, methods and apparatus related to thefield of semiconductor processing equipment are provided. Moreparticularly, the present invention relates to methods and apparatus fordepositing thin films, for example with gas distributors, used in theformation of integrated circuits. Merely by way of example, the methodand apparatus of the present invention are used in HDP/CVD processes.The method and apparatus can be applied to other processes forsemiconductor substrates, for example those used in the formation ofintegrated circuits.

FIG. 1A shows a previously known gas distributor. Gas distributor 10 hasa gas deflecting surface 12 and a gas distributor face 14. Gasdeflecting surface 12 provides a pathway for cleaning gases during achamber clean process. Cleaning gases are directed to the chamber wallsinstead of a substrate support member located directly below the gasdistributor. The gas distributor 10 is connected to a chamber wall at aproximal portion 16. During a CVD process, a deposition gas is suppliedto the gas distributor 10 at the proximal end 18. This deposition gasflows through gas distributor 10, exiting at apertures 20, and onto asubstrate position on the substrate support member. A step 22 extendscircumferentially around gas distributor face 14 to define an elevatedportion of gas distributor face 14. Several apertures 20 are disposed onthe gas distributor face 14 along step 22.

1. Exemplary ICP Chamber

Embodiments of the invention use the ULTIMA™ system manufactured byAPPLIED MATERIALS, INC., of Santa Clara, Calif., a general descriptionof which is provided in commonly assigned U.S. Pat. Nos. 5,994,662;6,170,428; and 6,450,117; and U.S. patent application Ser. Nos.10/963,030 and 11/075,527; the entire disclosures of these patents andapplications are incorporated herein by reference. An overview of theICP reactor is provided in connection with FIG. 1B. FIG. 1Bschematically illustrates the structure of an exemplary HDP-CVD system110 in one embodiment. The system 110 includes a chamber 113, a vacuumsystem 170, a source plasma system 180A, a bias plasma system 180B, agas delivery system 133, and a remote plasma cleaning system 150.

The upper portion of chamber 113 includes a dome 114, which is made of aceramic dielectric material, such as aluminum oxide or aluminum nitride,sapphire, SiC or quartz. A heater plate 123 and a cold plate 124surmount, and are thermally coupled to, dome 114. Heater plate 123 andcold plate 124 allow control of the dome temperature to within about±10° C. over a range of about 100° C. to 200° C. Dome 114 defines anupper boundary of a plasma processing region 116. Plasma processingregion 116 is bounded on the bottom by the upper surface of a substrate117 and a substrate support member 118.

The lower portion of chamber 113 includes a body member 122, which joinsthe chamber to the vacuum system. A base portion 121 of substratesupport member 118 is mounted on, and forms a continuous inner surfacewith, body member 122. Substrates are transferred into and out ofchamber 113 by a robot blade (not shown) through an insertion/removalopening (not shown) in the side of chamber 113. Lift pins (not shown)are raised and then lowered under the control of a motor (also notshown) to move the substrate from the robot blade at an upper loadingposition 157 to a lower processing position 156 in which the substrateis placed on a substrate receiving portion 119 of substrate supportmember 118. Substrate receiving portion 119 includes an electrostaticchuck 120 that secures the substrate to substrate support member 118during substrate processing. In a preferred embodiment, substratesupport member 118 is made from an aluminum oxide or aluminum ceramicmaterial.

Vacuum system 170 includes throttle body 125, which houses twin-bladethrottle valve 126 and is attached to gate valve 127 and turbo-molecularpump 128. It should be noted that throttle body 125 offers minimumobstruction to gas flow, and allows symmetric pumping. Gate valve 127can isolate pump 128 from throttle body 125, and can also controlchamber pressure by restricting the exhaust flow capacity when throttlevalve 126 is fully open. The arrangement of the throttle valve, gatevalve, and turbo-molecular pump allow accurate and stable control ofchamber pressures from between about 1 millitorr to about 2 torr.

The source plasma system 180A includes a top coil 129 and side coil 130,mounted on dome 114. A symmetrical ground shield (not shown) reduceselectrical coupling between the coils. Top coil 129 is powered by topsource RF (SRF) generator 13 1A, whereas side coil 130 is powered byside SRF generator 131B, allowing independent power levels andfrequencies of operation for each coil. This dual coil system allowscontrol of the radial ion density in chamber 113, thereby improvingplasma uniformity. Side coil 130 and top coil 129 are typicallyinductively driven, which does not require a complimentary electrode. Ina specific embodiment, the top source RF generator 131A provides up to2,500 watts of RF power at nominally 2 MHz and the side source RFgenerator 131B provides up to 5,000 watts of RF power at nominally 2MHz. The operating frequencies of the top and side RF generators may beoffset from the nominal operating frequency (e.g. to 1.7 1.9 MHz and 1.92.1 MHz, respectively) to improve plasma-generation efficiency.

A bias plasma system 180B includes a bias RF (“BRF”) generator 131 C anda bias matching network 132C. The bias plasma system 180B capacitivelycouples substrate portion 117 to body member 122, which act ascomplimentary electrodes. The bias plasma system 180B serves to enhancethe transport of plasma species (e.g., ions) created by the sourceplasma system 180A to the surface of the substrate. In a specificembodiment, bias RF generator provides up to 5,000 watts of RF power at13.56 MHz.

RF generators 131A and 131B include digitally controlled synthesizersand operate over a frequency range between about 1.8 to about 2.1 MHz.Each generator includes an RF control circuit (not shown) that measuresreflected power from the chamber and coil back to the generator andadjusts the frequency of operation to obtain the lowest reflected power,as understood by a person of ordinary skill in the art. RF generatorsare typically designed to operate into a load with a characteristicimpedance of 50 ohms. RF power may be reflected from loads that have adifferent characteristic impedance than the generator. This can reducepower transferred to the load. Additionally, power reflected from theload back to the generator may overload and damage the generator.Because the impedance of a plasma may range from less than 5 ohms toover 900 ohms, depending on the plasma ion density, among other factors,and because reflected power may be a function of frequency, adjustingthe generator frequency according to the reflected power increases thepower transferred from the RF generator to the plasma and protects thegenerator. Another way to reduce reflected power and improve efficiencyis with a matching network.

Matching networks 132A and 132B match the output impedance of generators131A and 131B with top coil 129 and side coil 130, respectively. The RFcontrol circuit may tune both matching networks by changing the value ofcapacitors within the matching networks to match the generator to theload as the load changes. The RF control circuit may tune a matchingnetwork when the power reflected from the load back to the generatorexceeds a certain limit. One way to provide a constant match, andeffectively disable the RF control circuit from tuning the matchingnetwork, is to set the reflected power limit above any expected value ofreflected power. This may help stabilize a plasma under some conditionsby holding the matching network constant at its most recent condition.

Other measures may also help stabilize a plasma. For example, the RFcontrol circuit can be used to determine the power delivered to the load(plasma) and may increase or decrease the generator output power to keepthe delivered power substantially constant during deposition of a layer.

A gas delivery system 133 provides gases from several sources, 134A-134Echamber for processing the substrate via gas delivery lines 138 (onlysome of which are shown). As would be understood by a person of skill inthe art, the actual sources used for sources 134A-134E and the actualconnection of delivery lines 138 to chamber 113 varies depending on thedeposition and cleaning processes executed within chamber 113. Gases areintroduced into chamber 113 through a gas ring 137 and/or a gasdistributor 111. In many embodiments, gas distributor 111 comprises afirst channel adapted to inject a source gas, such as SiH₄, and a secondchannel adapted to inject an oxidizer gas, such as O₂, which undergoes achemical reaction with the source gas to form SiO₂ on the substrate.Work in relation with embodiments of the present invention suggests thatsuch gas distributors can provide a uniform deposition of SiO₂ thatavoids silicon rich deposition in the central region of the substrate,for example embodiments that use gas rings with nozzles distributedaround the substrate near the side walls of the chamber.

In one embodiment, first and second gas sources, 134A and 134B, andfirst and second gas flow controllers, 135A′ and 135B′, provide gas toring plenum in gas ring 137 via gas delivery lines 138 (only some ofwhich are shown). Gas ring 137 has a plurality of source gas nozzles 139(only one of which is shown for purposes of illustration) that provide auniform flow of gas over the substrate. Nozzle length and nozzle anglemay be changed to allow tailoring of the uniformity profile and gasutilization efficiency for a particular process within an individualchamber. In a preferred embodiment, gas ring 137 has 12 source gasnozzles made from an aluminum oxide ceramic. In many embodiments, sourcegas nozzles 139 inject a source gas comprising SiH₄ into the chamber,which can be oxidized by an oxidizer gas, such as O₂, injected fromoxidizer nozzles to form the dielectric layer.

Gas ring 137 also has a plurality of oxidizer gas nozzles 140 (only oneof which is shown), which in a preferred embodiment are co-planar withand shorter than source gas nozzles 139, and in one embodiment receivegas from body plenum. In some embodiments it is desirable not to mixsource gases and oxidizer gases before injecting the gases into chamber113. In other embodiments, oxidizer gas and source gas may be mixedprior to injecting the gases into chamber 113 by providing apertures(not shown) between body plenum and gas ring plenum. In one embodiment,third, fourth, and fifth gas sources, 134C, 134D, and 134D′, and thirdand fourth gas flow controllers, 135C and 135D′, provide gas to bodyplenum via gas delivery lines 138. Additional valves, such as 143B(other valves not shown), may shut off gas from the flow controllers tothe chamber.

In embodiments where flammable, toxic, or corrosive gases are used, itmay be desirable to eliminate gas remaining in the gas delivery linesafter a deposition. This may be accomplished using a 3-way valve, suchas valve 143B, to isolate chamber 113 from delivery line 138A and tovent delivery line 138A to vacuum foreline 144, for example. As shown inFIG. 1B, other similar valves, such as 143A and 143C, may beincorporated on other gas delivery lines.

Chamber 113 also has a gas distributor 111 (or top nozzle) and top vent146. Gas distributor 111 and top vent 146 allow independent control oftop and side flows of the gases, which improves film uniformity andallows fine adjustment of the film's deposition and doping parameters.Top vent 146 is an annular opening around gas distributor 111. Gasdistributor 111 includes a plurality of apertures in a step according toan embodiment of the present invention for improved gas distribution. Inone embodiment, first gas source 134A supplies source gas nozzles 139and gas distributor 111. Source nozzle multifunction controller (MFC)135A′ controls the amount of gas delivered to source gas nozzles 139 andtop nozzle MFC 135A controls the amount of gas delivered to gasdistributor 111. Similarly, two MFCs 135B and 135B′ may be used tocontrol the flow of oxygen to both top vent 146 and oxidizer gas nozzles140 from a single source of oxygen, such as source 134B. The gasessupplied to gas distributor 111 and top vent 146 may be kept separateprior to flowing the gases into chamber 113, or the gases may be mixedin top plenum 148 before they flow into chamber 113. Separate sources ofthe same gas may be used to supply various portions of the chamber.

A baffle 158 is formed on gas distributor 111 to direct flows of cleangas toward the chamber wall and can also be used to direct flows ofremotely generated plasma and clean gas. As described in greater detailherein below, the gas distributor includes two separate channels thatpass two separate gases into chamber 113 where the gases mix and reactabove the semiconductor substrate.

A remote microwave-generated plasma cleaning system 150 is provided toperiodically clean deposition residues from chamber components. Thecleaning system includes a remote microwave generator 151 that creates aplasma from a cleaning gas source 134E (e.g., molecular fluorine,nitrogen trifluoride, other fluorocarbons or equivalents) in reactorcavity 153. The reactive species resulting from this plasma are conveyedto chamber 113 through cleaning gas feed port 154 via applicator tube155. The materials used to contain the cleaning plasma (e.g., cavity 153and applicator tube 155) must be resistant to attack by the plasma.Generating the cleaning plasma in a remote cavity allows the use of anefficient microwave generator and does not subject chamber components tothe temperature, radiation, or bombardment of the glow discharge thatmay be present in a plasma formed in situ. Consequently, relativelysensitive components, such as electrostatic chuck 120, do not need to becovered with a dummy wafer or otherwise protected, as may be requiredwith an in situ plasma cleaning process.

In FIG. 1B, the plasma-cleaning system 150 is shown below the chamber113, although other positions may alternatively be used, for exampleabove chamber 113 as described in U.S. application Ser. No. 10/963,030,the full disclosure of which has been previously incorporated herein byreference. In this alternate embodiment, the distance between thereactor cavity and feed port are kept as short as practical, since theconcentration of desirable plasma species may decline with distance fromreactor cavity. With a cleaning gas feed positioned at the top of thechamber above the baffle, remotely generated plasma species providedthrough the cleaning gas feed port can be directed to the sides of thechamber by the baffle.

System controller 160 controls the operation of system 110. In apreferred embodiment, controller 160 includes a memory 162, whichcomprises a tangible medium such as a hard disk drive, a floppy diskdrive (not shown), and a card rack (not shown) coupled to a processor161. The card rack may contain a single-board computer (SBC) (notshown), analog and digital input/output boards (not shown), interfaceboards (not shown), and stepper motor controller boards (not shown). Thesystem controller conforms to the Versa Modular European (“VME”)standard, which defines board, card cage, and connector dimensions andtypes. The VME standard also defines the bus structure as having a16-bit data bus and 24-bit address bus. System controller 160 operatesunder the control of a computer program stored on the tangible mediumfor example the hard disk drive, or through other computer programs,such as programs stored on a removable disk. The computer programdictates, for example, the timing, mixture of gases, RF power levels andother parameters of a particular process. The interface between a userand the system controller is via a monitor, such as a cathode ray tube(“CRT”), and a light pen.

System controller 160 controls the season time of the chamber and gasesused to season the chamber, the clean time and gases used to clean thechamber, and the application of plasma with the HDP CVD process. Toachieve this control, the system controller 160 is coupled to many ofthe components of system 110. For example, system controller 160 iscoupled to vacuum system 170, source plasma system 180A, bias plasmasystem 180B, gas delivery system 133, and remote plasma cleaning system150. System controller 160 is coupled to vacuum system 170 with a line163. System controller 160 is coupled to source plasma system I 80 witha line 164A and to bias plasma system 180B with a line 164B. Systemcontroller 160 is coupled to gas delivery system 133 with a line 165.System controller 160 is coupled to remote plasma cleaning system 150with a line 166. Lines 163, 164A, 164B, 165 and 166 transmit controlsignals from system controller 160 to vacuum system 170, source plasmasystem 180A, bias plasma system 180B, gas delivery system 133, andremote plasma cleaning system 150, respectively. For example, systemcontroller 160 separately controls each of flow controllers 135A to 135Eand 135A′ to 135D′ with line 165. Line 165 can comprise several separatecontrol lines connected to each flow controller. It will be understoodthat system controller 160 can include several distributed processors tocontrol the components of system 110.

2. Gas Distributor Characteristics

FIG. 2A shows cross sectional view of a gas distributor 200 having twochannels formed therein to separately pass a first fluid and a secondfluid according to an embodiment of the present invention. Gasdistributor 200 includes an upper end 208 located near a neck 206 thatsupports the gas distributor. Neck 206 includes threads adapted toattach the gas distributor to a support connected to fluid supply lines,for example gas delivery lines as described above. Gas distributor 200includes an upper surface 202 and a baffle 203. Baffle 203 includesupper surface 202 that is shaped to deflect a clean gas toward thechamber wall. Gas distributor 200 includes a lower surface 204. Lowersurface 204 is disposed opposite to upper surface 202. Lower surface 204includes a gas distribution surface 212 that is shaped to evenlydistribute deposition gases on the substrate below. Lower surface 204and gas distribution surface 212 include a step 220 to improve mixing ofgasses in the chamber. Step 220 includes at least one opening 244 formedthereon. Gas distributor 200 includes a channel 240 adapted to pass afirst fluid, for example a gas such as SiH₄. In alternate embodimentschannel 240 is adapted to pass a fluid that comprises a liquid. Channel240 extends from an opening 242, or inlet, at end 208 to the at leastone opening 244 formed in step 220. At least one opening 244 is disposedcircumferentially around gas distribution surface 212 along step 220.Gas distributor 200 also includes a second channel 230 adapted to pass asecond fluid, for example a gas such as O₂. In alternate embodimentschannel 230 is adapted to pass a fluid that comprises a liquid. Channel230 extends from an opening 232, or inlet, formed in first end 208 to anopening 234, or outlet, formed in lower surface 204. In manyembodiments, the SiH₄ fluid from channel 240 can undergo a chemicalreaction with the O₂ fluid from channel 230 to form SiO₂ that isdeposited on the substrate to form the dielectric layer. This chemicalreaction of the gases from the distributor in the chamber can reduce therichness of Si in the dielectric layer formed on the substrate. Gasdistributor 200 is typically made from a single piece of material, forexample a ceramic material comprising at least one of aluminum oxide(Al₂O₃), aluminum nitride (AlN), sapphire or silicon carbide. Whileembodiments of the present invention can be implemented with any gasdistributor, exemplary examples of gas distributors suitable forincorporating embodiments the present invention are described in U.S.application Ser. No. 11/075,527, the full disclosure of which has beenpreviously incorporated by reference.

FIG. 2B shows a bottom view of the gas distributor 200 as in FIG. 2Aaccording to an embodiment of the present invention. At least oneopening 244 includes 8 openings disposed circumferentially around gasdistribution surface 212 along step 220. While eight openings are shown,the at least one opening can include a range from 2 to 16 openings, forexample from 4 to 12 openings. Channel 240 includes as many branches asneeded to connect opening 242 with at least one opening 244, for example8 branches. Opening 234 is disposed centrally on gas distributor 200 andgas distribution surface 212. As gas distributor 200 is positionedcentrally in the chamber as described above, opening 234 is positionedcentrally in the chamber above the substrate support and substrate.While opening 234 is shown centrally in FIG. 2B, this opening can bedisposed anywhere along lower surface 204 and can include at least twoopenings, for example four openings disposed along lower surface 204.

FIG. 2C shows a cross sectional view of a connector 250 for gasdistributor 200 as in FIGS. 2A and 2B connected to a support 248 in asemiconductor process chamber according to an embodiment of the presentinvention. Support 248 includes a channel 260 that is connected to firstfluid supply line and adapted to pass the first fluid, and a channel 264that is connected to a second fluid supply line and adapted to pass thesecond fluid. The first fluid supply line, for example a gas deliveryline as described above, is connected to a flow controller under controlof the system controller as described above. The second fluid supplyline, for example a separate gas delivery line as described above, isconnected to a flow controller under control of the system controller asdescribed above. Thus, the system controller can separately control theflow of the first fluid through channel 260 and the flow of the secondfluid through channel 264. A chamber dome 282 includes an opening andsupport 248 extends downward into the opening to form an annular opening280. Clean gas can pass downward through annular opening 280 towardbaffle 203 under computer control as described above. Baffle 203deflects the clean gas from a first downward direction to a secondhorizontal direction away from the gas distributor and toward thechamber wall. Suitable clean gases include F₂, NF₃, CF₄, C₂F₈and O₂. Aseparate flow controller and gas delivery line as described above can beprovided for each of the gases to separately control injection of eachgas into the chamber. Channel 260 is aligned with channel 240 to passthe first fluid from channel 260 to channel 240. Channel 264 is alignedwith channel 230 to pass the second fluid from channel 264 to channel230.

A connector 250 rigidly attaches neck 206 to support 248. Gasdistributor 200 comprises components of connector 250. Connector 250includes a lock and key mechanism 252. Lock and key mechanism 252 isprovided to align gas distributor 200 with support 248 in apredetermined angular orientation so that the channels are aligned andthe first fluid passes to at least one opening 244 as intended and thesecond fluid passes to opening 232 as intended. Gas distributor 200comprises at least a portion of lock and key mechanism 250, for examplea lock (female end) that receives a key (male end) of the mechanism asshown in FIG. 2C. Connector 250 also includes a nut 270 with threadsthat rigidly attaches support 248 to neck 206 to support gas distributor200. During installation, nut 270 can be initially positioned downwardon neck 206 so that rotation of nut 270 will advance the nut upward andtoward the support to engage the support while the components of thelock and key mechanism are engaged. An O-ring 262 seals the connectionbetween channel 260 and channel 240 at upper end 208 of gas distributor200. An O-ring 266 seals the connection between channel 264 and channel230 at upper end 208 of gas distributor 200.

Referring again to FIGS. 2A to 2C, opening 234 is disposed centrally todirect a reactive fluid, for example O₂ gas, toward a center of asemiconductor substrate. Gas distributor 200 is positioned centrallyabove the semiconductor substrate and substrate support. As opening 234is located centrally on gas distributor 200, opening 234 is locatedcentrally above the substrate. A lower portion of channel 230 nearopening 234 is directed toward a central portion of the semiconductorsubstrate and points toward a central portion of the semiconductorsubstrate. This location of opening 234 and alignment channel 230 towardthe central region of the semiconductor substrate and support permitsimproved mixing of the reactive fluids provided by channels 230 and 240respectively. For example, channel 240 passes a first reactive fluidthat is oxidized, for example SiH₄ gas, and channel 230 passes a secondreactive fluid that is reduced, for example O₂. The first reactive fluidreacts with the second reactive fluid to form the desired molecularspecies, for example SiH₄ reacts with SiO₂ to form SiO₂. The centralinjection of O₂permits increased reaction of O₂ with SiH₄ to provide auniform layer of SiO₂ and avoids formation of a silicon (Si) rich layer.

FIG. 3A shows side cross sectional view of a quarter turn connector toattach a gas distributor in a predetermined orientation to a support ona gas supply line according to an embodiment of the present invention. Aconnector 350 rigidly connects a neck 306 of gas distributor asdescribed above to a support 348 on a gas supply line. Connector 350includes structures disposed on neck 306 to rigidly attach the gasdistributor to the gas supply line in the predetermined orientationshown. Support 348 includes a channel 360 that is connected to a firstfluid supply line and adapted to pass the first fluid, and a secondchannel 364 that is connected to a second fluid supply line and adaptedto pass the second fluid. Neck 306 of the gas distributor includes achannel 340 aligned with channel 360 to pass the first fluid asdescribed above. An O-ring 362 seal the connection of channel 360 withchannel 340. Neck 306 includes a channel 330 aligned with channel 364 topass the second fluid as described above. An O-ring 366 seals theconnection of channel 364 with channel 330. Dome 382 includes an openingand support 348 extends into the opening to define annular opening 380.Annular opening 380 is adapted to pass clean gas as described above.

Connector 350 includes structures adapted to provide rigid attachment ofneck 306 support 348 with a quarter (i.e. 90 degree) turn. For example,neck 306 includes a short flange 352 and a long flange 354. Support 348includes a narrow channel 356 and a wide channel 358 formed thereon.Narrow channel 356 is adapted to receive and mates with short flange352. Wide channel 358 is adapted to receive and mates with long flange354. The quick turn connector connects the gas distributor to thesupport with no more than half a turn, for example with a quarter turn.

FIG. 3B shows an upward looking cross sectional view of the quarter turnconnector of FIG. 3A according to an embodiment of the presentinvention. The connector on the gas distributor comprises structuresadapted to engage the support and limit rotation of the gas distributorat the predetermined orientation. Support 348 has a channel 357 formedthereon. Channel 357 is adapted to receive flange 352 and flange 354while the flanges are positioned in a first orientation that is rotated90 degrees from the position shown in FIG. 3B. In this first orientationthe flanges are aligned along channel 357. Upon rotation of the neck andflanges from the first orientation to the predetermined orientation,short flange 352 and long flange 354 move as indicated by arrows 359. Astop 355A engages long flange 354 and limits motion of the flange. Astop 355B engages short flange 352 and limits motion of the flange. Thusrotation of neck 306 in a counter clockwise direction as shown in FIG.3B causes the flanges to engage the stops and position the channels ofthe baffle and the baffle at the predetermined orientation in relationto the support and the channels of the support.

FIGS. 4A to 4C show installation of a quick turn connector 450 on a gasdistributor into a gas supply line support according to an embodiment ofthe present invention. A support 448 includes a channel 422 to pass afirst fluid and a channel 424 to pass a second fluid as described above.The quick turn connector connects the gas distributor to the supportwith no more than half a turn, for example with a quarter turn. Support448 also includes a channel 457. A gas distributor 400 includes achannel 412 to pass a first fluid as described above and a secondchannel 414 to pass a second fluid as described above. Gas distributor400 includes a long flange 410 and a short flange 411. Gas distributor400 is positioned in a first orientation to align flange 410 and flange411 along channel 457. Channel 457 receives the flanges of gasdistributor 400 as shown by arrow 458. As shown in FIG. 4B, flanges 410and 411 are inserted into channel 457. As shown in FIG. 4C gasdistributor 400 is rotated 90 degrees to the predetermined orientationso that flanges 410 and 411 engage the wide and narrow channels adaptedto receive and mate with the flanges as described above. As shown inFIG. 4C gas distributor 400 is aligned with support 448 in thepredetermined angular orientation so that channels 412 and 414 arealigned with channels 422 and 424, respectively, to pass the first andsecond fluids, respectively, as described above.

FIG. 5 shows a method 500 of processing a wafer with a gas distributorhaving two channels formed therein according to an embodiment of thepresent invention. A step 510 releases a clean gas into the chamber toclean the chamber. A step 520 seasons the chamber with a deposition gasto prevent contamination of the chamber. A step 530 places asemiconductor wafer in the chamber for processing. A step 540 applies anHDP/CVD voltage to the coils to generate plasma. A step 550 passes afirst fluid through a first channel in the body of the gas distributorand expels the gas into the chamber. A step 560 passes a second fluidthrough a second channel in the gas distributor and expels the secondfluid into the chamber. A step 570 mixes the first fluid and the secondfluid in the chamber outside the body of the gas distributor. A step 580deposits reactive products on the wafer with HDP/CVD process. A step 590removes the semiconductor wafer from the chamber. It should be notedthat many of the steps shown in FIG. 5 are performed at the same time orsubstantially the same time so that at least a portion of each step isperformed while at least a portion of another step is performed. Forexample, HDP voltage is applied to the coils with step 540, while thefirst fluid passes through the first channel with step 550 and thesecond fluid passes through the second channel with step 560 andreactive products are deposited on the wafer with step 580.

It should be appreciated that the specific steps illustrated in FIG. 5provide a particular method of processing a wafer according to anembodiment of the present invention. Other sequences of steps may alsobe performed according to alternative embodiments. For example,alternative embodiments of the present invention may perform the stepsoutlined above in a different order. Also, many of the steps may beperformed at the same time and at least partially overlap with respectto timing of the steps. Moreover, the individual steps illustrated inFIG. 5 may include multiple sub-steps that may be performed in varioussequences as appropriate to the individual step. Furthermore, additionalsteps may be added or removed depending on the particular applications.One of ordinary skill in the art will recognize many variations,modifications, and alternatives.

FIG. 6A shows cross sectional view of a gas distributor 600 with a firstchannel that comprises several branches that extend to a plurality offirst openings and a second channel with several branches that extend toa plurality of second openings according to an embodiment of the presentinvention. Gas distributor 600 has two channels formed therein toseparately pass a first fluid and a second fluid. Gas distributor 600includes an upper end 608 located near a neck 606 that supports the gasdistributor. Neck 606 includes threads adapted to attach the gasdistributor to a support connected to fluid supply lines, for examplegas delivery lines as described above, and has a first diameter. In analternate embodiment, the gas distributor includes a quick turnconnector as described above. Gas distributor 600 includes an uppersurface 602, or concave surface, and a baffle 603. Baffle 603 includesupper surface 602 that is shaped to deflect a clean gas toward thechamber wall. A lateral seat is disposed between neck 606 and uppersurface 602. Gas distributor 600 includes a lower surface 604. Lowersurface 604 is disposed opposite to upper surface 602. Lower surface 604includes a gas distribution surface 612 that is shaped to evenlydistribute deposition gases on the substrate below. Lower surface 604and gas distribution surface 612 include a step 620 to improve mixing ofgasses in the chamber. Lower surface 604 includes a central flat portionand a recessed peripheral flat portion separated from the central flatportion by step. 620. The central flat portion extends radially from acenter of lower surface 604 and has a second diameter greater than thefirst diameter of neck 606. Step 620 includes first openings 644, oroutlets, formed thereon. Gas distributor 600 includes a first channel640 adapted to pass a first fluid, for example a gas such as SiH₄. Inalternate embodiments first channel 640 is adapted to pass a fluid thatcomprises a liquid. Channel 640 extends from an opening 642, or firstinlet, at upper end 608 to first openings 644 formed in step 620. Firstopenings 644 are disposed circumferentially around gas distributionsurface 612 along step 620. Gas distributor 600 also includes a secondchannel 630 adapted to pass a second fluid, for example a gas such asO₂. In alternate embodiments second channel 630 is adapted to pass afluid that comprises a liquid. Second channel 630 extends from anopening 632, or second inlet, formed in upper end 608 to second openings634, or outlets, formed in lower surface 604. Gas distributor 600 istypically made from a single piece of material as described above.

FIG. 6B shows a bottom view of the gas distributor 600 as in FIG. 6Aaccording to an embodiment of the present invention. Openings 644include 8 openings disposed circumferentially around gas distributionsurface 612 along step 620. While eight openings are shown, openings 644can include a range from 2 to 16 openings, for example from 4 to 12openings. Channel 640 includes as many branches as needed to connectopening 642 with openings 644, for example 8 branches. FIG. 6C showseight branches of channel 640 extending to openings 644. Openings 634are disposed near the center of gas distributor 600 and gas distributionsurface 612. Openings 634 are disposed on the elevated central portionof lower surface 604. Channel 630 includes as many branches as needed toconnect opening 632 with openings 634, for example 4 branches. FIG. 6Dshows four branches of channel 630 extending to openings 634. As gasdistributor 600 is positioned centrally in the chamber as describedabove, openings 634 are positioned centrally in the chamber above thesubstrate support and a central portion of substrate. While openings 634are shown centrally in FIG. 6B, these openings can be disposed anywherealong lower surface 204, for example along the peripheral recessedportion of lower surface 604 outside step 620.

While the present invention has been described with respect toparticular embodiments and specific examples thereof, it should beunderstood that other embodiments may fall within the spirit and scopeof the invention. The scope of the invention should, therefore, bedetermined with reference to the appended claims along with their fullscope of equivalents.

1. A gas distributor for use in a semiconductor process chambercomprising a support, the gas distributor comprising: a body including:a neck having a first diameter, an upper end adjacent to the neck, afirst channel extending from a first inlet disposed on the upper end toat least a first opening disposed on a lower surface of the body, thefirst channel adapted to pass a first fluid from a first fluid supplyline in the support to at least the first opening, a second channelextending from a second inlet disposed on the upper end to at least asecond opening disposed on the lower surface of the body, the secondchannel adapted to pass a second fluid from a second fluid supply linein the support to at least the second opening, wherein the body isgenerally rotationally symmetric about an axis extending along the bodyfrom the neck to a center of the lower surface of the body, a connectorcoupled to the neck and adapted to engage the support and hold the bodyin a predetermined rotational orientation about the axis such that thefirst channel is substantially aligned with the first fluid supply lineand the second channel is substantially aligned with the second fluidsupply line, a lateral seat extending outward from the neck, a concavesurface extending from an outer periphery of the lateral seat outwardand toward the lower surface of the body, and a baffle disposed betweenthe concave surface and the lower surface of the body, wherein the lowersurface of the body includes a central flat portion and a recessedperipheral flat portion separated from the central flat portion by astep, the first opening disposed on the step and the second openingdisposed on the central flat portion, and wherein the central flatportion extends radially from the center of the lower surface of thebody to the step and has a second diameter greater than the firstdiameter.
 2. The gas distributor of claim 1 wherein the connector isadapted to connect the gas distributor to the support and seal the firstchannel to the first fluid supply line and the second channel to thesecond fluid supply line with no more than a half turn of the gasdistributor relative to the support.
 3. The gas distributor of claim 2wherein the connector comprises structures adapted to engage the supportand limit rotation of the gas distributor at the predeterminedorientation.
 4. The gas distributor of claim 2 wherein the connector isadapted to connect the gas distributor to the support and seal the firstchannel to the first fluid supply line and the second channel to thesecond fluid supply line with about a quarter turn of the gasdistributor relative to the support.
 5. The gas distributor of claim 1wherein the connector comprises a first flange and a second flange andwherein the flanges are adapted to support the gas distributor.
 6. Thegas distributor of claim 5 wherein the support comprises a channeladapted to receive the first flange while the connector and the supportare in a first orientation to insert the connector into the support, andwherein the flanges engage the support while the connector and thesupport are in the predetermined orientation.
 7. The gas distributor ofclaim 6 wherein the flanges are adapted to engage the support with aquarter turn of the gas distributor from the first orientation to thepredetermined orientation.
 8. The gas distributor of claim 1 wherein thebody is formed from a single piece of material.